Production of alcohols and ketones by the oxidation of cycloaliphatic or araliphatic hydrocarbons



2,938,924 DATION CNS 4 Sheets-Sheet 1 ATT'YS ET AL ETONES BY THE OXI 0RARALIPHATIC HYDROCARB W. SIMON COHOLS AND K PRODUCTION OF AL OFCYCLOALIPHATIC a, 1956 FIG. I

w u 4 I INVENTORS'. WALTER SIMON HANS JOACHIM WALDMANN ERNST $LAUTH B 1I @4 W May 31, 1960 Filed June 1 y 31, 1960 w. SIMON 21-. 2,938,924

PRODUCTION OF ALCOHOLS AND KETONES BY THE OXIDATION OF CYCLOALIPHATIC ORARALIPHATIC HYDROCARBONS Filed June 13, 1956 4 Sheets-Sheet 2 FIG. 2

27 I6 Y 7 f 26 H- H 2| 0 g 2 a M E 33 h A 3| 35 3s 40 a2 42 39 34 4a 482a 45 46 L E INVENTORS:

WALTER SIMON HANS JOACHIM WALDMANN ERNST PLAUTH 9 w. SIMON ETAL2,938,924

PRODUCTION OF ALCOHOLS AND KETONES BY THE OXIDATION 3 OF CYCLOALIPHATICOR ARALIPHATIC HYDROCARBONS 4 Sheets-Sheet 3 Filed June 1 FIG. 3

.. N n N O A T M N D E V L m A N H m m H l A sm w E T TSS NN AR WHE ATTYs y 1960 w. SIMON ETAL 2,938,924

PRODUCTION OF ALCOHOLS AND KETONES BY THE OXIDATION OF CYCLOALIPHATIC 0RARALIPHATIC HYDROCARBONS Filed June 13, 1956 4 Sheets-Sheet 4 FIG. 4

Illlllllllllll INVENTORS:

WALTER SIMON HANS JOACHIM WALDMANN ERNST PLAUTH ATT'YS PRODUCTION OFALCOHOLS AND KETONES BY THE OXIDATION OF CYCLOALIPHATIC OR ARALIPHATICHYDROCARBONS Walter Simon and Hans Joachim Waldmann, Ludwigshafen(Rhine), and Ernst Plauth, Bad Duerkheim, Germany, assignors to BadischeAnilin- & Soda-Fabrilr Aktiengesellschaft, Ludwigshafen (Rhine), GermanyFiled June 13, 1956, Ser. No. 591,087 Claims priority, applicationGermany June 15, 1955 Claims. (Cl. 260-586) carbons to alcohols andketones by treatment with oxygen or oxygen-containing gases is known inthe art. In the practice of the prior art processes, however, acidproducts were obtained in varying amounts as by-products and this, as aresult, not only reduced the yield of the oxidation products sought, butalso further reduced the yields of alcohols by ester formation betweenthe acid products and the alcohols. The separation of the oxidationmixture is also rendered considerably more diflicult because of thepresence of the esters.

In a known method, these shortcomings, in particular the formation ofesters, are avoided by carrying out the oxidation of the hydrocarbons inthe presence of added water, the amount of water added being betweenabout 10 and 30% by weight with reference to the amount of hydrocarbon(US. Patent No. 2,565,087). This processing technique not only has thedisadvantage that with the same space-time yields of oxidation products,such as alcohols and ketones, the capacity of the oxidation vessel mustbe considerably increased, but also the added water acts as an inhibitorby removing from the reaction zone substances which accelerate thereaction. Moreover when catalysts are used, their action is reduced.

In the method described in US. Patent No. 2,557,281, not only is feed ofwater to the oxidation vessel avoided, but even the water arising fromthe oxidation is removed immediately after its formation and stripped inseparators from the hydrocarbons, which are returned to the oxidationzone. This method has the shortcoming that deposits of the acids,otherwise solid at room temperature, will occur in the connection linescausing clogging of the lines with consequent interruptions in theoperation.

The primary object of this invention is toprovide a simple method,capable of being carried out on an industrial scale, for the oxidationof cycloaliphatic or araliphatic hydrocarbons in the liquid phase withoxygen, air or other oxygen-containing gases which makes it possible towork in continuous operation without trouble and in which esterformation is substantially suppressed.

A further object of the invention is the oxidation of cycloaliphatic oraraliphatic hydrocarbons in a plurality of successive oxidation zonesand the maintenance of the content of acids, which are by themselvesvery valuable by-products, in the oxidation vessels and in thedistillation processing of the oxidation mixture within such limits thatthey do not separate.

Another object is to minimize the formation of esters by the removal ofthe major proportion of the acidic oxidation products in the oxidationmixture emergingv from at least one oxidation zone.

A still further object of the invention is the removal from theoxidation mixture of the acid components, as far as their presenceinterferes with carrying out the process in the individual oxidationstages, by Washing.

with water the oxidation mixture resulting from at least one oxidationzone, to obtain an oxidation product of a composition which lends itselfespecially advantageous ly to further processing and from which thedesired alcohols and ketones are separated readily in good yields andgood purity.

A still further object of the invention is to provide higher efiiciencyin the distillation processing of the reaction mixture into itscomponents, the distillation being rendered extremely cheap and economicby an extensive utilization of the energy, in particular the heat,available.

Still another object of the invention lies in the use of a definite typeof reaction vessel for the practice of the oxidation. Other objects ofthe invention will appear from the following description.

We have found that the oxidation of cycloaliphatic or araliphatichydrocarbons in the liquid phase to form the alcohols and ketones can becarried out with special efiiciency and without the disadvantageshereinbefore described by passing the hydrocarbons at elevatedtemperature, if desired with the addition of oxidation catalysts,through a plurality of successive reaction vessels while introducinginto said vessels a gaseous oxidizing agent, such as a gas containingoxygen. The oxidation products are washed with water at least onceduring the processing advantageously after they emerge from the lastreaction vessel and the oxidation products are separated by distillationfrom the unreacted initial hydrocarbons. Another step in the process ofour invention involves at least one treatment of the water Washedoxidation mixture with aqueous solutions of basic-reacting alkalicompounds, such as alkali metal hydroxides or carbonates.

As gases containing oxygen in accordance with the invention there can beemployed air, air enriched with or deprived of oxygen and oxygen itself.

Preferred alkali metal hydroxides or carbonates for use in the practiceof our invention are the hydroxides and carbonates of sodium andpotassium metal. It is advantageous to use them in a concentration of 5to 35%, advantageously 10 to 25% by weight. Suitable cycloaliphatic oraraliphatic hydrocarbons are in particular cycloparafiins, as forexample cyclohexane or cyclo-octane, and also ethylbenzene and otheralkylbenzenes having two or more, in particular 2 to 6, carbon atoms inthe side chain.

The oxidation is carried out at elevated temperatures, as for examplebetween about and 170 C. The optimum temperatures differ with theparticular hydrocarbon reactant used. In the case of cycloparaflins theylie below 150 C., forexample at to C. for cyclohexane. The reaction iscarried out at atmospheric or superatmospheric pressure, as for exampleat 2 to 50 atmospheres.

The preferred type of reaction vessels are those having a tubularinsertion, in which the inner tube is positioned either on center or offcenter of the reaction vessel. The inner tube has a cross-section of 20to 70% of the overall cross-section of the vessel and is positioned inthe inner space of the vessel to provide a free space at both ends. Thetube can be secured to the inner wall of the vessel at difierent places.The initial material and oxygen-containing gas, such as air, areintroduced into the inner tube. A part of the liquid reaction product,

Patented May 31, 1960 consisting of unreacted feed stock and oxidationproduct, is withdrawn together with the oxygen-containing gas at theopposite end of the reaction vessel. If the gas is removed at theopposite end, the liquid reaction mixture can also be removed fromcirculation at the inlet side. The other part of the reaction mixtureflows back into the intermediate space between the tube and vessel walland again enters the interior of the tube so that a circulation isproduced. The initial material and the oxygencontaim'ng gas can also beintroduced into'the intermediate space with the aid of one or morenozzles so that a part of the reaction mixture flows back through theinterior of'the tube and then passes again, into the intermediate space.In general the volume circulated perhour in such vessels amounts. tomore than ten times, often 20 to 50 times, the'total volume contained111 the vessel.

To prevent the reaction temperature rising beyond a permissible degreecooling may be necessary, for example by providing cooling aggregates inthe circulation, system or by withdrawing, part of the circulatedreactants and products, passing them through a cooler outside thevesseland then returning them to the vessel. The circulation of the reactantsand products in the vessel can also be intensified by pumping themthrough a recycle pipe situated outside the vessel. On the other handvessels without the tubular insertion may be used-the circulationprovided by one or more external pipes with circulatory pumps therein.

Suitable catalysts for use in the oxidation are the conventional typeoxidation catalysts, as for example metals, in particular cobalt andalso cerium, nickel, iron, lead, titanium, vanadium, chromium,molybdenum, uranium, manganese, platinum, silver, tin, calcium ormagnesium. Oil-soluble salts of these metals are especially suitable, asfor example naphthenic acid or monoor dicarboxylic acid salts. Inorganiccompounds of metals, as for example oxides or halides, sulfates,phosphates, vanadates, inolybdates, tungstates and chromates can also beused. The catalysts can also be applied to carriers, such as bleachingearths, synthetically-made silicates, active aluminas, magnesia or zincoxide. Further substances which accelerate oxidation, such as peroxides,can be coemployed. The catalysts are added to the hydrocarbons to beoxidized or to the oxidation mixture in amounts of 0.1 to 200 grams ofmetal to 1,000 kilograms of hydrocarbon or oxidation mixture. It isadvantageous to work with 0.3 to 40 grams of metal to 1,000 kilograms ofhydrocarbon or oxidation mixture.

In the practice ofour invention the initial material as a feed stock,preferably in preheated condition, is charged in the first reactionvessel, with oxygen or oxygen-containing gas being'simultaneously fed inin fine dispersion, for example by spraying at room temperature or atemperature ranging between 20 and 100 C. When needed, oxidationcatalysts may also be fed in in a finely divided form, e.g. by'spraying.The feed stock is preferably preheated to a temperature which lies about10 to 50 C. below the oxidation temperature. About 20 to 70 cubic metresof air, for example, are introduced into the vessel for each 1,000kilograms of hydrocarbon or of liquid oxidation mixture.

The reaction mixture is withdrawn for example at a point opposite to thepoint of entry, and introduced into the second reaction vessel, ifnecessary with further supply of oxygen or oxygen-containing gases andof catalysts. After passing through this vessel it is led in the sameway through any further vessel, for example through'five reactionvessels. The residence time in the entire reaction zone preferablyamounts to at least 15 minutes, advantageously'40 minutes and more, asfor example 1 to 3 hours and more. At least after passage through onestage, advantageously at least after the last oxidation stage, andpreferably after each stage, water is :fed in in anamount of 0.3 to 5%by weight, in partic- 4 ular 0.5 to 3% by weight with referenceto thereaction mixture. It is advantageous thereafter to cool thewatercontaining mixture, if desired without decompression, in a cooleror heat exchanger to a temperature which lies about 20 to 70 C. belowthe oxidation temperature. The heat set free by the cooling of themixture is preferably utilized by heat exchange to preheat the hydro--carbon mixture before the first reaction stage, and also may beemployed'to evaporate extensively the oxidation mixture afterdecompression on the way to the first distillation column.

The aqueous layer is stripped in a separator, it contains the majorpart, for example 50 to of the undesired acid oxidation products formed.The nonaqueous layer is led into the next oxidation vessel or to adistillation column, as the case may be, after a short washing with anaqueous solution of a basic-reacting alkali metal compound, such as ametal hydroxide or alkali metal carbonate, and separation from theaqueous washing phase.

The water can be introduced in an amount of 0.3 to 5%, in particular 0.5to 3%, also into the last'part of the reaction vessel in which oxidationno longer takes place. In this case the vessels, having inbuilt tubesdescribed above have proved especially suitable. The water is resuppliedat various points to the recycle or the OXygGnr. containing gas. Theaqueous layer is withdrawn at the lower part of the vessel. Above theaqueous layer, part of the liquid reaction mixture can be withdrawn inso far as it has not already been withdrawn overhead with the gas.Special regard should be had to. the fact that no larger amounts ofwater areused because otherwise ,the' course of the reaction is retardedand the yield lowered.

The alkaline washing solutions preferably used are from 5 to.3.0%aqueous solutions of sodium or potassium metal hydroxide or carbonate.The amount of solution used may be from about one quarter to about fourtimes the amount of the oxidation product to be treated. The washing iscarried out at elevated temperature, advantageously above 60 C., forexample at 65 to C. It is of advantage to follow each Washing withalkali by a washing with water. Preferably in each separator, but atleast in the last separator, the gases also are stripped. The gases arecooled, for example to room temperature, and treated with washingsolutions. As washing solutions in the gas strippers, the oxidationproduct or fractions thereof, asfor example cyclohexanone orcyclohexanol or the residueleft after distillingotf thecyclohexanonecyclohexanol fraction, are especially suitable. It ispreferable to use about 0.2 to 4 kilograms of solvent foreach cubicmetre of gas for the washing of the gases.

The non-aqueous portion of the oxidation mixture is then separated bydistillation. Thiscan be effected by a short residence time inVaporizers or preferably by lo nger residence times in a plurality ofsuccessive distillation columns at rising temperatures. In the lattercase it; is preferable to separate in the first column thebulk'of thenon-oxidized hydrocarbon. The temperature in the sump of this columnlies at about 20 to 50 C. above the boiling temperature of thehydrocarbon, i.e., at about 100 to C. in the case of cyclohexane.

The residue-is then freed from the remaining fraction of the unconvertedhydrocarbon in the second column at a higher temperature, for example atabout the boiling temperature of the oxidation product of lowestgboilingpoint, as for example cyclohexanonc, and if desiredsplit up into itsalcoholic and ketonic components in further distillation columns. If thedistillation is carried .out:.in stages, the alkaline treatment can becarried. out after thefirst distillation column. This treatment iscarried out for example with an oxidation mixturelwhich .still .containsat least 20% of non-oxidized: hydrocarbons. The alkaline :treatment canhoweverfbe .carriedrout-in the same way after the practically. completeseparationiof the non-oxidized hydrocarbons. I

A specially preferred separation of the oxidation mixture, and one whichisespecially advantageous from the point of view of economy in heat, maybe achieved by carrying out the distillation in stages, the pressure inthe first stage being so much higher than in the second stage that thevapors leaving the first stage of the distillation provide by indirectheat exchange the heat of vaporization wholly or for the most part, andpreferably also at least a part of the reflux heat, for the secondstage.

Since considerable amounts, as for example up to 95%, of hydrocarbons oflow boiling pointare contained in the mixture leaving the last oxidationstage, and a high reflux ratio is needed for their separation at thenecessary sharpness of separation, the utilization of the heat energy ofthe vapors leaving the first distillation stage is of great economicaladvantage. An embodiment of this distillative method of processing isshown by way of example in Figure 4 of the accompanying drawings andwill now be described in greater detail. i

The reaction mixture consisting of hydrocarbons and oxidation products,especially alcohols and ketones, enters the distillation apparatus at 1.In a preheater 2, which is heated with low pressure steam by a coiledtube 3, the oxidation product is preheated to a temperature of about 95C. and the mixture of vapor and liquid introduced at the bottom into thedistillation column 4 which is kept under a pressure of 1.5 atmospheres.The constituents of highest volatility, i.e. the hydrocarbons, leave atthe top of column 4 through a pipe 5. The vapors are condsensed in aheat exchanger 6 and led with the aid of a pump 7 through a pipe 25 to areservoir (not shown). Part of the hydrocarbons is branched oii througha pipe 8 and returned as a reflux into the upper part of the column 4through a valve 9. The fraction of the oxidation product vaporized atthe same time from the up-risin-g hydrocarbon vapors is driven back byrectification into the residue. In the sump of the column 4 such anamount of heat is supplied by a heating coil 4' that the reflux iswholly or partly vaporized.

The mixture occurring in the sump of the distillation column 4, whichcontains, in addition to the oxidation products, in particular alcoholsand ketones, also hydrocarbons in amounts of from 85 to 90%, withreference to the mixture contained in the sump, is decompressed to about0.3 atmosphere through a valve 10. In this Way a part, for example 10%,of the mixture, in particular low boiling hydrocarbon components, isvaporized. A further major part of the hydrocarbons which still remainliquid and a part of the oxidation product evaporate in the exchanger 6by indirect heat exchange with the vapors leaving the column 4 throughpipe 5, which are condensed. The mixture of vapors and fractions of themixture withdrawn through pipe 10 which have not yet vaporized isintroduced into a column 12 which is additionally heated by sump heating13. The column 12 operates under a reduced pressure of about 0.2 to 0.25atmosphere, the diminished pressure being maintained by a vacuumapparatus, for example a vacuum pump. The distillate escapes at theupper part of the column 12 through a pipe 15 and is condensed in acooler 16 cooled with water and pumped through a collecting vessel 17and pump 18 through a pipe 25 to a reservoir (not shown). In order thatin the column 12 the up-rising vapors be fractionated and the oxidationproducts held back from the escaping hydrocarbon vapors, a part of thehydrocarbons is introduced as reflux into the upper part of the columnthrough a valve 14. By heating means 13, such an amount of heat issupplied to the column 12 that the reflux is wholly or partly vaporized.Further heat of vaporization can also be supplied by the heating means13. In the latter case not only does the reflux vaporize completely, butalso additional, partially liquid parts of the initial productintroduced into the column 12 are vaporized, The residue collecting atthe bottom of the column 13 is forced by pump' 20 through a preheater21, which is heated with high pressure steam of 20 excess atmospheres,into distillation column 22.

Column 22 works at about the pressure of column 12. In the preheater 21as well as in the sump heating 23 of the column 22, the residualfractions of the hydrocarbon, which are still mixed with the oxidationproduct withdrawn at the bottom of the column 12, are vaporized.Fractions of the oxidation product vaporized therewith arefractionatedout and held back for the most part by the introduction of hydrocarbonsfrom the pipe 8 through valve 24 into the upper part of column 22. Thevapors leaving at the top of the column 22, which contain mainlyhydrocarbons with also slight traces of oxidation products, are suppliedagain to the column 12 through pipe 11. The oxidation product free fromhydrocarbons is withdrawn at the bottom of column 22 and conveyed by apump 26. v

The rectification can also be carried out entirely in the last stage by.condensing the hydrocarbons leaving at the top of column 22 in a specialcondenser. In this case the column 22, can be kept under any pressure,as for example atmospheric pressure.

For the first vaporization of the hydrocarbons in the preheater 2 theremay preferably be utilized the heat inherent in the mixture to be workedup from the precedingoxidation of the hydrocarbons, which must bewithdrawn between the reaction vessels.

The following examples will further illustrate this invention but theinvention is not restricted to these examples.

Example 1 5 cubic metres of cyclohexane which has been heated to 100 C.in a preheater 1 are fed per hour at a pressure of 30 atmospheres into areaction vessel 4 (see Figure 1 of the accompanying drawings) having acapacity of 1.55 cubic metres from a container 41 by means of a pump. Atthe same time 100 cubic metres of air per hour are fed in through a pipe2, while 15 grams per hour of cobalt are sprayed in through pipe 3 inthe form of an aqueous solution of cobalt acetate. The temperature inthe reaction vessel is about 140 C. and is kept constant by the airintroduced cold and the preheated cyclohexane.

The hot oxidation mixture which leaves the reaction vessel 4 togetherwith exhausted air at a rate of 5 cubic metres per hour at a temperatureof 140 C. is mixed continually with 30 kilograms of water per hourthrough the pipe 5, cooled to about C. in the cooler 6 and freed inseparator 7 from the aqueous layer which is run ofi through pipe 8. Theoxidation mixture substantially freed from acid components, as well asthe exhausted air are sprayed into the reaction vessel 12 after havingpassed the intermediate preheater 9. The mixture of liquid and air ismixed when introduced in reaction vessel 12 with cubic metres of air atroom temperature per hour through the pipe 10 and 15 grams of cobalt inthe form of an aqueous solution of cobalt acetate through pipe 11. Thetemperature in the vessel 12 also amounts to 140 C. and is maintained inthe same way as in the vessel 4 in spite of the heat of reaction setfree by the added cold air and the reaction mixture entering at about100 to C.

From the reaction vessel 12, the mixture leaving at a temperature of C.,which has been further oxidized up to about 3.5% with reference to theamount of cyclo hexane supplied to vessel 4 per hour, is led through acooler 14 where it is cooled to about'90 C. after 30 kilograms per hourof water have been continuously added to it through pipe 13. From theseparator 15 the aqueous phase is withdrawn through pipe 16. To thenon-aqueous phase 75 kilograms per hour of a 25% aqueous sodiumhydroxide solution are added through a pipe 17. From the separator 18,the liquor containing the neutralized acid components is withdrawnthrough pipe aosagsa.

7 19, while through pipe 20 the exhausted air escapes and the o 'dat onmixture is withdrawn at ahoutthe" middle of the separator. This is thenled to a reaction vessel 24 after passing the preheater 21. At the sametime 100 cubic metres of air are led per hour through pipe 22 and 235grams of cobalt in the form ofthe catalyst solution already mentionedare introduced. The oxidation temperature in the reaction vessel 24 alsoamounts to 140 C. The oxidation mixture and the exhausted air, whichleave the reaction vessel 24 at the top are mixed with 30 kilograms ofwater through pipe '25, the water being added continuously. The mixtureis cooled to 90 to 100 C. in a cooler 26 and then brought intotheseparator 27.

The aqueous phase is run off through pipe 28' while the.

air escapes through pipe 29. It is united with the waste air flowing outthrough the pipe 20 and cooled to'20" C. in the cooler 30. Thecondensate, which consists mainly of cyclohexane, is passed throughseparator and pipe 32 to the container 41. I

The uncondensed cold gases flow from the separator 31 into the washer33, in which they are washed .with oxidation product free fromcyclohexane which is supplied through pipe 34 from the colum 49, andallowed to escape through pipe 35. 200 kilograms of washing liquor arethus introduced into the washer per hour.

The washing liquor laden with cyclohexane withdrawn from the sump of thewasher 33 is united through pipe 36 with the product supplied from theseparator 27 through pipe 37 and passed through vaporizer 38 to adistillation column 39. The coolers 6, 14, 26 and 30 maybe in heatexchange with the vaporizer 38 and preheaters 1, 9 and 21.

Inthe column 39 there distills over at about 100C. sump temperature thebulk of the unconverted cyclohexane. It is liquefied in the condenser 40and supplied to the container 41.

The residue of the distillation column 39, which still contains about60% of cyclohexane, is withdrawn from the bottom of the column, mixedper hour with ,65 kilograms of a 12% aqueous caustic soda solutionsupplied through pipe 42 and passed into separator 43. The aqueousalkaline liquor is separated through pipe 44. The non-aqueous layerflows into separator 46 after 50 kilograms per hour of water have beenadded thereto through pipe 45. The water is run off from the separator46 through pipe 47 and can be used for the preparation of the causticsoda solution. The washed product from the separator 46 is led through apreheater 48 into a distillation column 49 where the. remainingcyclohexane is distilled ofi at a sump temperature of about 160 C.

Thecyclohexane is condensed in a cooler 50 and then passed to thecontainer 41. The residue from the distillation column 49 consists of40% of cyclohexanone, about 52% of cyclohexanol and about 8% ofcomponents of higher boiling point. A part thereof, amounting to about180 kilograms per hour, is run off into a collecting vessel 52 while theremaining part-is supplied through pipe 34 toa washer 53.

Through pipe 53, fresh cyclohexane is supplied from a container (notshown) to the container 41 at the rate at which it is used up by theoxidation.

The oxidation mixture freed from acid components and unreactedhydrocarbons which collects in the collecting vessel 52 may if desiredbe further separated into cyclohexanol and cyclohexanone by aconventional fractional distillation under reduced pressure, for exampleat to 100 torr.

From the washing liquor run off through pipes 8, 16 and 28 there areobtained per hour as by-product about kilograms of adipic acid bydistilling off 10 to of the-water together with dissolved hydrocarbons,cooling, crystallizing out and filtering ofi. amount can be; recoveredby working'up .the alkaline wash n swa About twice the 8 Example 2 Froma container 30 (see Figure 2 of the accompanying drawings) 8 cubicmetres per hour of cyclohexane are led under a pressure of 40atmospheres through a preheater '1 into a reaction vessel 4 which isheated to C. and which has a capacity of 3.2 cubic metres. At the sametime 300 cubic metres per hour of air at room temperature are ledthrough a pipe 2 and 20 grams of cobalt in the form of a solution ofcobalt naphthenate in cyclohexane through a pipe 3. Through the commoninlet pipe, cyclohexane, air and catalyst solution are mixed withreaction mixture circulating in the reaction vessel at 140 C. and thereaction temperature 01f 140 C. thereby kept constant.

75' kilograms of water per hour are mixed through a pipe 5 with theoxidation mixture which leaves the reaction vessel with the exhaustedair. The mixture is cooled to 95 C. in a cooler 6 and separted into itsphases in a separator 7. The aqueous phase with the dissolved acids isrun off from the separator 7 through a pipe 8, while the exhausted air,laden with cyclohexane vapor, is allowed to escape through a pipe 9. Theoxidation mixture, still containing a small amount of acid (about 0.2%by weight) is brought to a temperature of C. by a preheater 10 and ledinto a reaction vessel 13 of 3.2 cubic metres capacity, there beingmixed with the mixture per hour 250 cubic metres of cold air through apipe 11 and 10 grams of cobalt in the form of a cobalt naphthenatesolution in cyclohexane through a pipe 12. i

The further oxidized mixture leaves the reaction vessel 13 with theexhausted air at C. 90 kilograms per hour of water, supplied through apipe 14, are added, the whole cooled in a cooler 15 to 90 C. andseparated in a separator 16. The water laden with acid components is runofi through a pipe 17 and the exhausted air through a pipe 18.

The air flowing from the pipes 9 and 18 is cooled to 20 C. in a cooler19, freed in a separator 20 from condensed cyclohexane (which iswithdrawn through a pipe 21 and returned to the container 30) and led toa washer 22 filled with filler bodies. In this the gas is washed freefrom cyclohexane with 200 kilograms per hour of oxidation product fed inthrough pipe 23. The oxidation product with the absorbed cyclohexane isdecompressed through a pipe 25. It is united with the oxidation mixturefree from water and gas which is decompressed through a pipe 26 from theseparator 16, and led through a preheater 27 into a column 28. The gaseswashed out in the washer 22 are allowed to escape through a pipe 24.

In the column 28, the bulk of the unreacted cyclohexane (about 90 byweight) is distilled off, condensed in a cooler 29 and collected in thecontainer 30. The sump of the column, with a content of 25% ofcyclohexane, is led through a preheater 31 into a column 32. .Thecyclohexane distilled off from the top of the column .is condensed in acooler 33 and also collected in the container 30. As a sump thereremains in thecolumn 32 an oxidation product completely freed fromhydrocarbon.

The oxidation product free from cyclohexane (of which 600 kilograms perhours are obtained and which still has an acid number of 60 and an esternumber of 50) is withdrawn from the sump of the column 32 and suppliedthrough a pipe 34 to treatment with alkalisolution. Part of the productis branched off through'a pipe 34 and supplied through the pipe 23 tothe washer22 in the amount already described.

The treatment with alkali solution takes place in the c rculation pipe35in which 400 kilograms of oxidation product from the pipe 34 andkilograms of a 20% aqueous caustic soda solution from the pipe 37per-hour are stirred up by a pump 36. The treated mixture is sup pliedfrom the cycled mixture through a pipe 38 to a centrifuge39. The aqueousphase flows through a pipe 40, while the product separated from thealkali solution flows through a pipe 41. The product withdrawn throughthe pipe 41 in an amount of 350 kilograms per hour has 80 kilograms ofwater added to it through a pipe 42 and after mixing in a mixer 43 isled into a centrifuge 44. This separates the water through a pipe 45.The product free from water and acid (335 kilograms per hour) flows oilthrough a pipe 46 into a container 47. The cyclohexane used up for theoxidation is replaced by fresh cyclohexane which is supplied through apipe 48 to the container 30. Cyclooctane can be oxidized in an analogousmanner, cyclooctanone and cyclooctanol being obtained as the mainproducts. In addition suberic acid and low molecular acids are obtained.

Example 3 From a cyclohexane reservoir 42 (see Figure 3 of theaccompanying drawings) 6.5 cubic metres per hour of cyclohexane areconveyed by means of a pump 1 under a pressure of 50 atmospheres througha heater 2 to a reaction vessel 3, the temperature of the cyclohexanethus being raised to 100 to 110 C. 200 cubic metres per hour of air areadmixed through a pipe 4 and 5 grams per hours of manganese in the formof an alcoholic solution of manganese chloride through a pipe 5. Themixture is sprayed through a nozzle d into the inner central circulationtube a of the reaction vessel 3. The reaction vessel has a capacity ofabout 2 cubic metres. The mixture circulating in the reaction vessel,which is further heated by the heat of oxidation set free, is kept at atemperature of 145 C. The oxidation mixture (6.5 cubic metres per hour)from the reaction vessel 3 (which contains about 2.5% of oxidationproductsmainly cyclohexanol and cyclohexanone, besidesfacids and esters)is led together with the exhausted air through a pipe 6 and through acooler 7 and thus cooled to about 80 C. Through a pipe 8, a further 200cubic metres per hour of air at room temperature are admixed andsupplied to the reaction vessel 9. The reaction vessel 9 has a capacityof about 4 cubic metres and a central circulation tube u This is of suchlength and so arranged that below and above the circulation there areseparating chambers a and b each occupying about one fifth of the totalspace in the reaction vessel. The mixture supplied to the reactionvessel 9 is introduced through nozzles d into the annular space betweenthe inner circulation tube and the jacket of the reaction vessel. Thetemperature of the circulating mixture is kept at 140 C. The exhaustedair is separated in the upper separating chamber while maintaining aliquid level. The air drawn oif through a pipe 10 is cooled to C. in acooler 11 and led through a separator 12 and a pipe 13 to a washer 14oxidation product from container 46. The cold outgoing air, washed freefrom cyclohexane, is released from pressure and allowed to escapethrough a valve 15.

The fraction of hydrocarbons condensed in the cooler 11 is run ofi? fromthe separator 12 through a pipe 23.

In the reaction vessel 9 about 110 kilograms per hour of aqueoussolution from the pipe the central circulation tube al through which theoxidation mixture, practically free from air, flows back. In the lowerseparation chamber b of the reaction vessel 9, the aqueous solution isseparated and decompressed and allowed to escape through a valve 17.This solution contains about 70% of the acids and acid esters formed inthe oxidation reation vessels 3 and 9 as well as other oxidationproducts and has a concentration of about 40% by weight of these organicsubstances.

Above the aqueous phase in the reaction vessel 9, the oxidation mixture,after a total of about 5% of the cyclohexane has been oxidized, iswithdrawn, cooled to about 90 C. in a cooler 18 and washedcountercurrently in a washer 19 with 100 kilograms of water per hourinand therein washed with the 16 are added through 10 troduced through apipe 20. During the washing the water absorbs the acid compounds stillpresent in the oxidation mixture. From the lower end of the washer 19the wash water is supplied by means of a pump 21 through the pipe 16 tothe reaction vessel 9. I

The washed oxidation mixture, which now contains about 4% of theoxidation product in the cyclohexane, is united through a pipe 22 withthe condensate from the separator 12 conveyed through a pipe 23; 70kilograms per hour of a 20% by weight aqueous caustic soda solution froma pipe 25 are added in pipe 24 and introduced into a separator 26. Thealkali solution neutralizes and absorbs the free acids left and at thesame time saponifies the bulk of the ester, the acids being absorbed.The aqueous solution is then decompressed through valve 27.

, The oxidation mixture which is now neutral is decompressed down toabout 1.5 atmospheres through a valve 28 and through a vaporizer 29 intoa distillation column 30. The heater 2 and vaporizer 29 may be in heatexchange relation with the coolers 7, 11 and 18. About two-thirds ofcyclohexaneis distilled off in the distillation column 30 under apressure of 1.5 atmospheres. The enriched oxidation mixture occurring inthe sump of the column 30 is united with the washing oil laden withcyclohexane and coming from the washer 14 through valve 31 and pipe 32,and mixed in a pipe 33 with 20 litres per hour of a 10% by weightaqueous caustic soda solution. -The caustic soda solution, which isintroduced through a pipe 34, is separated again in a separator 35 andrun off through a valve 36. The enriched oxida: tion mixture isdecompressed through a valve 37 to a pressure of 0.5 atmosphere andextensively vaporized in a heat exchanger 38 with the aid of condensingvapors coming from the column 30. In a subsequent column 39, thecyclohexane is completely distilled off, condensed in a cooler40 andconveyed by a pump 41 to a cyclohexane container 42. The cyclohexanecondensed in the heat exchanger 38 and coming from the distillationcolumn 30 is also collected in the container 42 through a valve 43. Theamount of cyclohexane used up is replenished through a pipe 44. Theamount of cyclohexane supplied per hour through the pipe 44 amounts toabout 250 kilograms.

The oxidation product free from cyclohexane occurring in the sump of thecolumn 39 (consisting per hour of kilograms of cyclohexanone, 220kilograms of cyclehexanol and 20 kilograms of products of higher boilingpoint) is conveyed by means of a pump 45 to a reservoir 46. From this200kilograms per hour are conveyed through a pipe 47 and a pump 48 tothe gas washer 14. kilograms of the oxidation-product collected in thecontainer 39 are withdrawn per hour through a pipe 49 to be separated bydistillation.

The saving in energy in the separation of the nonoxidized hydrocarbonsfrom the oxidation product by distillation, which. is obtained bycarrying out the distillation in a plurality of stages, the pressure inthe first stage being so much higher than that of the second stage thatthe vapors leaving the first stage wholly or mainly supply the heat ofevaporation and if desired also part of the reflux heat for the secondstage, is illustrated by the following example.

Example 4 For the separation by distillation of an oxidation mixturewhich has been obtained, as described in the foregoing examples, byoxidation of cyclohexane and accumulates in an hourly amount of 10,000kilograms of unreacted cyclohexane (95%) and 500 kilograms of oxidationproduct (5%), it would be necessary for the recovery of pure cyclohexaneby conventional distillation to add about 30% of the amount of thedistillate, i.e. 3,000 kilograms per hour of reflux liquid to the headof the rectification column. Thus 13,000 kilograms per hour ofcyclohexane would have to be vaporized a heat expenditure of about1,000,000 KcaL/hour;

"Bywork ng acc ording to Figure 4, about 4,000 kilograms of cyclohexaneper hour are vaporized in vaporizer 2 by means of low pressure steam ata pressure of 6 atmospheres. The vapors are dephlegmated in column 4with 1,200 kilograms 'per hour of cyclohexane at a pressure of ljatmospheres and at about 90 C. The heat for the vaporization'of thereflux is provided by a heating coil situated in the column throughwhich low pressure steam of about 6 atmospheres flows.

5,200 kilograms of yclohexane vapor flow at 90 C. into the'heatexchanger 6 and are condensed therein. The heat of condensation servesfurther to vaporize the mixture coming from valve 10 which has beendecompre'ss'ed down to a pressure of 0.2 atmosphere, and in fact aboutthe equivalent amount of cyclohexane, namely 5,200'kilograms per hour,is evaporated so that 5,200 kilograms of vapo'rous cyclohexane entercolumn 12 together with vaporized portions of the oxidation product andamixture of only'800 kilograms of liquid cyclohexane and the bulk of theoxidation product. The vaporization temperature of this mixture withabout 60% of cyclohexane "amounts to about 60 C. at 0.2 atmosphere sothat a heat interval of about 30 C. is present in the heat exchanger 6.i

Into the column 12 there must be introduced again 30% of 5,200kilograms, i.e. about 1,500 kilograms,'of reflux for rectification. Theheat necessary for this 'is produced inthe heating means 13/ Theremaining 800 kilograms of cyclohexane are vaporized in the preheater21; In the sump heating means 23, the heat necessary for vaporization of30%:240 kilogram of reflux is produced. i

' In all therefore the following amounts of cyclohexane are vaporized byexternal supply of energy;

Kilograms/hour Preheater 2 4,000 Sump heating 4 1,200 Sump heating 131,500 Preheater 21 800 S ump heating 23 240 Total 7,740

As compared with the vaporization of 13,000kilograms per hour thisrepresents a saving of heat of 41%. I

If in this process the utilizable reaction heat arising in the oxidation(400,000Kcal.%hour) is used in the heat'exchang'er 2 for thevaporization, about 1000 kilograms of'cyclohexane can'be vaporized inthe preheater 2. In this case the amounts of cyclohexane to be vaporizedby external supply of heat are only as follows:

Kilograms/ hour Sump heating 4 200 Sump heating 13 1,500 Pheheater 21800 Sump heating 23 240 Total 2,740

As compared with the vaporization of 13,000 kilograms per hour, thisrepresents a saving of heat of 7 9%.

What we claim is: i

1. A process for production of alcohols and ketones by oxidation ofcyclic hydrocarbons from the group consisting of cyclohexane,cycle-octane, and alkyl benzenes having from 2 to 6 carbon atoms intheir alkyl chain by passing the cyclic hydrocarbons in the liquid"phase through successive oxidation zones and therein contacting thecyclic hydrocarbons with gases'containing oxygen at temperatures fromabout l'20170 C. and pressures from atmospheric up to 50 atmospheres,separating the unreacted hydrocarbons from the cyclic hydrocarbonpartial oxidation productis 'containingf alcohols and'keto'n'es, and,

thepartial' oxidation products, washing the oxidation mixture ofpartially oxidized products and unreacted hydrocarbons at least oncewith water to remove water soluble carboxylic acids resulting fromthepagtial oxidation andthereafter'washing the oxidation mixture of thepartially oxidized products and unreacted hydrocarbons at least oncewith an aqueous solution of an alkali metal alkaline compound selectedfrom the group consisting of alkali metal hydroxides and alkali metalcarbonates. 2. The process according to claim l wherein, after thewashing steps in accordance with the process of claim 1, the bulk of theunreacted hydrocarbons are distilled from the oxidation mixture, theresidual oxidation mixture'of the distillation step is washed with anaqueous solution of an alkali metal alkaline compound selected from thegroup consisting of alkali metal hydroxides and alkali metal carbonates,the aqueous solution of alkali metal alkaline compound is separated fromthe washed, residual mixture, and the unreacted hydrocarbon remaining inthe residual mixture is then distilled oil? from the partial oxidationproducts consisting essentially of alcohols and ketones. i 1

3. A process according to claim 1 wherein, after the washing steps inaccordance with the process of claim 1, the unreacted hydrocarbons aresubstantially completely separated from the oxidation mixture of partialoxidation products and unreacted hydrocarbons, the separated partialoxidation products are washed with an aqueous solution alkali metalalkaline compound, selected from the group consisting of alkali metalhydroxides and alkali metal carbonates, and the aqueous washing solutionis separated from the washed partial oxidation products.

4. A process for production of alcohols and ketones by oxidation ofcyclic hydrocarbons from the group conone of the oxidation zones,cooling the water-organic.

mixture resulting from the water-washing step, separating the washingwater from the cooled Waterorganic mixture, and thereafter washing thewater-washed oxidation mix-' ture of partially oxidized products andunreacted hydrocarbons at least once with an aqueous solutionof analkali metal alkaline compound selected from the group consisting ofalkali metal hydroxides and alkali metal carbonates.

5. The process according to claim 4 wherein the waterwashing step iscarried out between two successive oxidation zones, the water-organicmixture is cooled to a tern perature 20 C.-70 C. below the oxidationtemperature, and the water-washed organic mixture, after separation ofthe water phase therefrom, is again heated to an oxidation temperaturein the range of -170 C. before it is conducted to the next oxidationzone.

6. A process for production of alcohols and ketones through at least twosuccessive oxidation zones and therein contacting the cyclichydrocarbons with gasesv containing oxygen at temperatures from about12.0-

C. and pressures from atmospheric up to 50 atmospheres, washing withwater the oxidation mixture of; partially oxidized products andunreacted hydrocarbons, exiting from each zone, and, at least after thelast water-washing of'the oxidation mixture, fiurther waishing themixture of partially oxidized products and unreacted hydrocarbons atleast once with an aqueous solution of an alkali metal alkaline compoundselected from the group consisting of alkali metal hydroxides and alkalimetal carbonates.

7. The process according to claim 6 wherein the waterwashing after eachoxidation zone is carried out by mixing the Water with the hot oxidationmixture exiting from each oxidation zone, the water-organic mixture iscooled to about 20-70 C. below the oxidation temperature, and the washwater phase is separated from the cooled water-organic mixture.

8. The process according to claim 6 wherein the number of water-washingsteps in one less than the number of oxidation zones employed in theprocess of claim 6.

9. A process for the production of alcohols and ketones by the oxidationof cyclic hydrocarbons from the group consisting of cyclohexane,cyclo-octane, and alkyl benzenes having from 2 to 6 carbon atoms intheir alkyl chain by passing the cyclic hydrocarbons in the liquid phasethrough successive oxidation zones and therein contacting the cyclichydrocarbons with gases containing oxygen at temperatures from about120-170 C. and pressures from atmospheric up to 50 atmospheres, washingthe oxidation mixture of partially oxidized products and unreactedhydrocarbons at least once with water to remove watersoluble carboxylicacids resulting from the partial oxidation, thereafter distilling ofifrom the oxidation mixture the bulk of the unreacted hydrocarbons,washing the resulting residual oxidation mixture of the distillationstep with an aqueous solution of an alkali metal alkaline compoundselected from the group consisting of alkali metal hydroxides and alkalimetal carbonates, separating the aqueous solution of the alkali metalalkaline compound from the washed, residual mixture and thereafterdistilling off the unreacted hydrocarbon remaining in the residualmixture from the partial oxidation products consisting esesntially ofalcohols and ketones.

10. A process for production of alcohols and ketones by oxidation ofcyclohexane by passing cyclohexane in the liquid phase throughsuccessive oxidation zones and therein contacting the cyclohexane withgases containing oxygen at temperatures from about l20-l70 C. andpressures from atmospheric up to atmospheres, separating the unreactedhydrocarbon from the cyclohexane partial oxidation products containingalcohols and ketones, and, prior to separation of the unreactedhydrocarbons from the partial oxidation products, washing the oxidationmixture of partially oxidized products and unreacted hydrocarbons atleast once with water to remove water-soluble carboxylic acids resultingfrom the partial oxidation and thereafter washing the oxidation mixtureof the partially oxidized products and unreacted hydrocarbon at leastonce with an aqueous solution of an alkali metal alkaline compoundselected from the group consisting of sodium hydroxide, sodiumcarbonate, potassium hydroxide, and potassium carbonate.

References Cited in the file of this patent UNITED STATES PATENTS2,552,670 Fleming May '15, 1951 2,557,281' Hamblet et al. June 19, 19512,609,395 Dougherty Sept. 2, 1952 2,825,742 Schueler et a1 Mar. 4, 1958UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,,938924 May 315 1960 Walter Simon et al0 It is hereby certified that errorappears in the printed specification of the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 8 line 19 for 'separted" read M separated line 62 for -'hours"read hour ==-g column 9 line 68 for "reation read reaction column llline 40 for heating 4" read heating 4" line 4.9 for "Kcal %h0ur" readKcal./hour column 13,, line 14 for "in one" read is one Signed andsealed this 29th day of November 1960.,

(SEAL) Attest:

KARL Ho AXLINE ROBERT C. WATSCFN Attesting Ofiicer Commissioner ofPatents

1. A PROCESS FOR PRODUCTION OF ALCOHOLS AND KETONES BY OXIDATION OFCYCLIC HYDROCARBONS FROM THE GROUP CONSISTING OF CYCLOHEXANE,CYCLO-OCTANE, AND ALKYL BENZENES HAVING FROM 2 TO 6 CARBON ATOMS INTHEIR ALKYL CHAIN BY PASSING THE CYCLIC HYDROCARBONS IN THE LIQUID PHASETHROUGH SUCCESSIVE OXIDATION ZONES AND THEREIN CONTACTING THE CYCLICHYDROCARBONS WITH GASES CONTAINING OXYGEN AT TEMPERATURES FROM ABOUT120-170*C. AND PRESSURES FROM ATMOSPHERIC UP TO 50 ATMOSPHERES,SEPARATING THE UNREACTED HYDROCARBONS FROM THE CYCLIC HYDROCARBONPARTIAL OXIDATION PRODUCTS CONTAINING ALCOHOLS AND KETONES, AND, PRIORTO SEPARATION OF THE UNREACTED HYDROCARBONS FROM THE PARTIAL OXIDATIONPRODUCTS, WASHING THE OXIDATION MIXTURE OF PARTIALLY OXIDIZED PRODUCTSAND UNREACTED HYDROCARBONS AT LEAST ONCE WITH WATER TO REMOVEWATERSOLUBLE CARBOXYLIC ACIDS RESULTING FROM THE PARTIAL OXIDATION ANDTHEREAFTER WASHING THE OXIDATION MIXTURE OF THE PARTIALLY OXIDIZEDPRODUCTS AND UNREACTED HYDROCARBONS AT LEAST ONCE WITH AN AQUEOUSSOLUTION OF AN ALKALI METAL ALKALINE COMPOUND SELECTED FROM THE GROUPCONSISTING OF ALKALI METAL HYDROXIDES AND ALKALI METAL CARBONATES.